sys.modules is consulted before sys.meta_path, so everything site pulls
in from .pth files -- setuptools' _distutils_hack and 24 editable-install
finders on a dev host -- resolved straight out of the cache and never
reached the Blocker. An overlay with a smuggled 'import _distutils_hack'
passed the guard before this change and fails after it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The env generator runs on the bare bootstrap python, before any
dependency is installed. utils/distros.py reached PyYAML through
utils.cache.yaml, so `python -m cli.meta.env` died with
ModuleNotFoundError on every dev-runtime image that ships python3
without PyYAML.
utils/yaml_bootstrap.load_block reads the block-YAML subset the SPOT
files use with stdlib only. It raises BootstrapYamlError on anything it
cannot parse identically to yaml.safe_load, so meta/distros.yml fails
loud instead of drifting.
The per-line regex lint meant to guard this is gone: one hop of
indirection defeated it and it stayed green while the invariant was
broken. It is replaced by a test that runs the real generator with
every non-stdlib import blocked.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
kevinveenbirkenbachandClaude Opus 5